The overall goals of these investigations are to (a) establish animal models to study long-term effects on behavior and development of perinatal viral infection of the central nervous system, and (b) to correlate the existence of and mechanisms for behavioral and developmental alterations with other investigations on various types of encephalopathy produced by the same viral pathogens. Lymphocytic choriomeningitis virus has been found to produce alterations in the growth and behavior of adult rats following intracerebral inoculation as neonates. Employing such methods as virus titration, serology, fluorescent immuno- and histochemistry, routine pathology, and behavioral testing, these studies will attempt to clarify the pathogenesis of factors responsible for these developmental retardations. Comparisons will be made using other types of neurotropic viruses, such as West Nile and rabies viruses, along with varying age at infection, in order to develop models of mental retardations of viral etiology.